Refining titanium bearing materials



United States Patent 2,702,757 REFINING TITANIUM BEARING MATERIALSMonroe J. Bahnsen, deceased, late of Lakewood, Ohio, by Jane Bahnsen,executrix, Lakewood, Ernest H. Goda, East Cleveland, and Glenn H.McIntyre, Cleveland Heights, Ohio, assignors to Ferro Corporation, acorporation of Ohio No Drawing. Continuation of application Serial No.657,902, March 28, 1946. This application July 28, 1951, Serial No.239,192

1 Claim. (Cl. 106-312) This invention is a continuation of our inventionSerial Number 657,902 filed March 28, 1946, and now abandoned.

This invention relates to a new product rich in compounds of titaniumand especially useful as a smelter addition agent or component in themanufacture of porcelain enamel frit.

Titanium oxide has been used in the manufacture of porcelain enamels butusually the same has been the socalled pigment grade prepared by any oneof several prior art processes. This pigment type material, whileextremely valuable in organic coating materials such as paints, becauseof its tremendous hiding power and other properties is not particularlysuitable for use in the manufacture of porcelain enamels. In the firstplace, this material is quite expensive and in the second place, itssmall particle size has required elaborate precautions and pre-mixingprocedures before it could be used satisfactorily in the production ofglasses and porcelain enamel.

One of the most economical and widely available sources of titanium isrutile. That mineral, however, contains sufficient quantities ofimpurities such as compounds of chromium and vanadium so as to render itincapable of use directly as a source of titanium compounds, since suchimpurities have a discoloring effect on the enamels when fired onto thework.

It is a principal object of our invention to provide a titanium bearingmaterial which may be used as a smelter component in the manufacture ofporcelain enamels, which material is derived from rutile by a processwhich is quite inexpensive, while at the same time eliminatingsufiiciently the impurities such as the chromium and vanadium compounds.

It is a further object of our invention to provide an improved porcelainenamel characterized by the inclusion therein as a smelter component, aproduct prepared in accordance with our invention.

Other objects of the invention will appear as the description proceeds.

To the accomplishment of the foregoing and related ends, said inventionthen comprises the features hereinafter fully described and particularlypointed out in the claims, the following description setting forth indetail certain illustrative embodiments of the invention, these beingindicative, however, of but a few of the various ways in which theprinciple of the invention may be employed.

Broadly stated this invention comprises the provision of a newcomposition useful as a smelter component in the manufacture ofporcelain enamel frit, which composition may be defined as the productderived by sintering rutile with an amount of soda ash in excess of thatrequired to convert the titania content of the rutile to thetri-titanate, comminuting the sintered mass, and then water washing suchcomminuted sintered mass sufliciently so as to leach therefromsubstantially all of the chromates and vanadates, leaving as the endproduct a material which may be utilized directly as a titanium richsource of material to be included as a smelter component in porcelainenamels.

As previously indicated, the starting material used in the production ofour improved product is rutile. Any commercial grade of that mineral maybe employed since the process for the production of our improved productwill result in the removal therefrom of such imice purities as wouldotherwise be found detrimental to the porcelain enamel. The precisecomposition of the product which we have thus provided for the purposesabove stated is diflicult to determine exactly. For this reason, it isbelieved preferable to identify the product by its method of production,which in the main includes the following principal steps.

The rutile is first admixed with an amount of soda ash as previouslyindicated in excess of that required to convert the titania content ofthe rutile to the tri-titanate. After the rutile and soda ash arethoroughly intermixed, the mixture is sintered at a temperature of fromabout 1550 F. to about 2000" F. for a length of time sufiicient tocomplete the reaction. A time of from /2 to 8 hours may be used for thissintering operation depending upon the mass of the material beingsintered and the heat input into the furnace.

During the sintering operation the above specified major components ofthe sintered mass may have admixed therewith a minor amount of amaterial such as sodium chloride which is effective to lower the meltingpoint of the mass and thus facilitate the sintering operation.Additionally or alternatively, the sintered mass may have includedtherein a minor amount of an oxidizmg agent such as sodium nitrate orsodium chlorate.

The oxidizing agent and the material used to lower the melting point ofthe mass will, as indicated, be used in' and this step is preferablyaccomplished by dumping the hot sintered mass into water, whichquenching action has the effect of breaking up the sintered mass andalso performing a desirable initial leaching step.

After the sintered mass thus projected into the water bath has beenpermitted to cool, it is'then comminuted, preferably by beingball-milled with water to a fineness such that at least will passthrough a 325 mesh screen.

At this point it should be observed that the fineness of the startingmaterial rutile has an important bearing on certain of the conditions ofthe process required to produce our new product. 'The fineness ofsubdivision of titamum compounds therein has a direct bearing on thelength of time required during the sintering operation for the reactionbetween the rutile and the soda ash to go to completion. For this reasonI prefer to employ as a starting material rutile which has beenpulverized to such an extent that substantially all of it will passthrough a 325 mesh screen.

Instead of employing a ball-mill and thus grinding the sintered mass inwater to a fineness such that at least 95%, or preferably substantiallyall, will pass through a 325 mesh screen, we may for larger batches andlarge scale commercial operations use a dry grinding procedure such asthat performed by well known available apparatus. After the sinteredmass has thus been comminuted, 1t 18 then water washed preferably usinghot water until the water washed solution is completely colorless. Inthis connection it should be noted that the original wash water is adeep yellow due to the solution therein of chromates formed during thesintering operation.

After the product has been washed until there is no longer any trace ofcolor in the wash water, the product 1s then dried and is ready for useas a smelter component in the manufacture of porcelain enamel.

As illustration of the process above explained, refer- A ence may be hadto the following example.

l00 parts of rutile having approximately the following analysis:

was thoroughly mixed with 75 parts of soda ash contaming about 44 partsof NaaO and with 15 parts of so- 3 dium nitrate containing'about 5.45parts of Nazi). The ratio of "H02 to NazO'was thus about 95 to 49.45.

The mixture above identified was sintered at a tempera ture of about1650" F. in an oxidizing atmosphere for a period of about 6 hours, afterwhich the sintered mass was thrown hot into Water, allowed to cool andball-milled with water until substantially all of the solid materialpassed through a 325 mesh screen. The water was then removed byfiltration and the milled mass subjected to a continuous washing untilthe wash water was absolutely colorless. The dried product showed thefollowing approximate analysis:

TiO

As previously indicated, our invention includes not only the. Provisionof. this improved titanium bearing material which may be used as. asmelter component in the manufacture of porcelain enamel frit, but suchinvention also includes porcelain enamels made by the utilization ofsuch materials, since. such enamels have an improved color be cause. ofthe. substantial absence of any amounts of chromium and vanadiumcompounds which otherwise would have atendency to discolor the enamel.

As. illustration of the types of porcelain enamels within which ourimproved material may be employed as a F component, reference may be hadto the following table which gives. in parts by weight the variousmaterials which are added to the smelter and smelted under customaryconditions.

35 1,929,521 Ryan Oct. 10, 1933 2,496,993 Goda Feb. 7, 1950 OTHERREFERENCES 0 Perry, Chemical Engineers Handbook, 2nd edition,

1941, page 1256.

, 2200. F. and Composition B should be smelted for a period of from 3 to4 hours at a temperature of from 2100 F. to 2300 F The frit compositionsgiven above, or more accurately the components thereof other than thematerial of this invention, will be recognized as more or lessconventional acid resisting enamels and are given merely as illustrativeof porcelain enamels generally within Evhich the material of thisinvention will be found use ul.

Other modes of applying the principle of the invention may be employed,change being; made as regards the details described, provided thefeatures stated in any of the following claims or the equivalent of suchbe employed.

We therefore'particularly point out and distinctly claim as ourinvention:

The process of making a composition, useful as a smeltor component inthe manufacture of porcelain enamel, which consists essentially ofsintering a commercial rutile bearing minor amounts of. chromium andvanadiumiwith from about 50% to 100% by weight of commercialsoda ash inthe presence of up to 25% by weight of the futile. ofa material selectedfrom the class consisting of sodium chlorate and sodium nitrate: at atemperature from about 1550 F. to about 2000 F., comminuting thesintered mass, and then Water washing such comminuted sintered masssufliciently to leach out substantially'all of the chromates andvanadates.

References Cited in the file of this patent UNITED STATES PATENTS

